Lubricant



Patented Mar. 7, 1939 UNiTEo STATES 2,149,271 LUBRICANT John G. Butz, Philadelphia, Pa., assignor to The- Atlantic Refining Company, a corporation of Pennsylvania Philadelphia, Pa.,

No Drawing. Application June 20, 1936, Serial lilo, 86,345

10 Claims.

The present invention relates to theart of lubrication, and more particularly to thelubrication of surfaces engaging under extreme pressure, as

' temperatures of 210 for example, the rubbing surfaces of hypoid gears,

free wheeling transmissions, speed reducers and the like.

'I'he'general tendency in the design of modern machinery has'been toward a higher ratio between power and dead weight. This is especially true in the automotive industr and in recent years certain types of gears and other mechanisms have been developed with the operating pressures on the working surfaces so high that ordinary mineral oil lubricants will not provide sufficient lubrication for satisfactory operation. Heretofore it has been thought that lubrication consists in maintaining a film of oil between the rubbing surfaces, thereby preventing them from coming into contact with one another and thus preventing wear. That this condition exists in well lubricated bearings is well known, but this conception of lubrication does not apply to highly loaded gears. In well lubricated bearings the loads rarely exceed 2000 lbs. per sq. in. projected area and the rubbing speeds are generally high enough to maintain a film of oil which separates the rubbing surfaces. In automobile gears, the pressures between gear teeth reach very high values and even the most viscous oils or greases cannot be retained between the surfaces of the teeth in a sufllciently thick film to prevent metal to metal contact, particularly when operating encountered.

It has. been known that compounded lubricants bined chlorine, possess, lubricating qualities which render operating pressures.

function satisfactorily would cause failure of These compounded oils an unblended mineral oil,

it used alone. It is believed that the-successful use of such compounded olls depends upon the adsorption and reaction-or union of certain components of these oils with the metal surfaces whereby a film of metallic compound, such as, for example,'iron' sulfide or chloride is formed. It

appears that such a film or'platingjhas a low coeflicient of friction between the bearing'surfaces. The hydrocarbon oil constituent of an extreme pressure lubricant F. or higher are commonly them suitable for use'under high.

under conditions which andthat s tisfactoryo era,- tion of heavily loaded bearings or gears depends 'aryl phosphines. Furthermore, the phosphines I may contain halogen, for example, ,chlorine, bromine or fluorine. The formula for these com- I pounds maybe generally represented as:

wherein R R", and R may be aliphatic, aromatic, hydro-aromatic or hetercyclic functions. R and R may be substituent functions while R may be hydrogen, or R may be a substituent function while R and R are hydrogen.

The aliphatic phosphines may be exemplified by tri-methyl phosphine and its homologues, triethyl, tri-propyl, tri-butyl, and the like. The aromatic phosphines may be represented, for example, by tri-phenyl phosphine and its homologues, tri-tolyl, tri-xylyl, as well as the phosphines containing the naphthyl and anthracyl functions and their homologues. Among the hydroaromatic phosphines may be included tri-cyclohexyl phosphine, trl-tetrahydronaphthyl phosphine, and the like. The phosphines. which contain mixed functions may be illustrated by dibutyl monophenyl phosphine; mono-ethyl ditolyl phosphine, and the like. Theheterocyclic phosphines are ex-v emplified by tri-furylphosphine, tri-pyridyl, and tri-thienyl phosphine. The halogenated phosphines include the chlorine, bromine and fluorine derivativesof all of the above mentioned -compounds and may be represented specifically, for example; by chloro-tri-butyl.phosphine, chlorotri-phenyl phosphine,- and. bromo-di-butyl monotolyl phosphine. The phosphines; are not necessarlly'limited to thetri-substituted derivatives, since compounds such I isoamyl, phosphine.; and monoandj diphenyl phosphine may be suitably employedlfl,

In preparing my lubricant, I add to a suitable mineral oil one ora' mixture of two or more of the phosphines in quantity suflicient to improve 5 as diethyl phosphine, di-' I extent, depending upon the operating'conditions under which the lubricant is-to be used. I have found that the quantityof phosphine required,

in general, does not exceed substantially 5% by weight of my composition. Quantities of the phosphine as smalljas 3%, or even 1% or less, have been found toimprove lubricating oils to a satisfactory extent. In certain instances, 0.1% to 0.2% by weight of the phosphine was suflicient to improve the lubricating oil to the desired extent. In preparing my lubricant, I may obtain a homogeneous solution or stable suspension of thephosphine in mineral oil by agitating the mixture at normal or elevated temperatures, or I may dissolve the phosphine in a suitable solvent and add the resulting solution to the oil, thereafter removing the solvent by vaporization.

The mechanism by which the phosphines in lubricating oils function to improve the loadl-bearing ability and other properties thereof is not entirely understood. It.appears, however, that the functioning is dependent upon the adsorption of the compounds upon the metal surfaces of the bearings or other lubricated parts, and the reaction or chemical combination of such compounds with the metal under the influence of localizedhigh temperature and pressure to form a coating orplating having a low coeflicient of friction which is resistant to seizure under high operating pressures.

Typical examples are as follows: I

(1) 99 parts by weight of a lubricatingoil having a Saybolt universal viscosity at 100 F. of 37.6

of my improvedglubricant seconds and an A. P. I. gravity of 291 was admixed with l partby weight of tri-phenyl phosphine and a homogeneous solution was obtained. Upon testing the lubricant in an Almen extreme pressure lubricant testing machine at 200 R. P. M., a pressure of 21,000 lbs./sq. in. projected bearing area was sustained before seizure of the bearing occurred, whereas the unblended lubricating oil failed at a pressure of 4,000 lbs./sq. in. projected bearing area.

(2) 99.5 parts by weight of the lubricating oil mentioned in Example 1 was admixed with 0.5 part by weight of tri-phenyl phosphine, and this lubricant, when tested in the Almen testing machine at 200 R. P. M. sustained a load of 14,000 lbs/sq. in. projected bearing area, whereas the unblended lubricating oil failed at a pressure of 4,000 lbs./sq. in. projected bearing area.

It will, be seen, from the above examples, that the addition of a phosphine to a hydrocarbon oil improves the lubricating value 'of such an oil to a marked degree, and imparts to the oil certain properties which render it suitable for use in the lubrication of surfaces engaging under extreme pressure. Under certain conditions, for example in the lubrication of transmissions or gear drives where elevated temperatures are not normally encountered, it has been found that the halogenated, and" particularly the chlorinated phosphines are more efficient than the unchlorinated compounds in their ability to improve the load-bearing capacity of the lubricants. .Furthermore, I have found that phosphines having as substituents long hydrocarbon chains or substituted hydrocarbon chains, are capable of not only improving the load-bearing capacity of hydrocarbon oils but also effect a lowering of the coemcient offriction, or improve the oiliness of the lubricant. The phosphines containing long chain alkyl radicals such as cetyl, lauryl,

dodecyl and oleyl, and the substitution products thereof, are representative examples of this type of materials.

While I have described my invention with reference to the lubrication of gears and bearings operating under heavy loads, I do not intend to limit myself thereto, but contemplate the use of my lubricant in operations such as the cutting and boring of metals, in which conditions of extreme pressure and temperature are normallyencountered, and also in the lubrication of mechanisms operating under moderate pressures, as for example, the crankcase bearings and cylinder walls of internal combustion engines. Furthermore, my compounded oil may be utilized as a base in the preparation of thickened oils, i. e., greases, by the addition thereto of soaps or other conventional thickening agents, in order to obtain lubricants of desired viscosity. My compounded oil may also be blended with fatty oils, fatty acids, synthetic esters and the like, or the phosphines, per se, may be admixed with fatty oils, for the lubrication of mechanisms in which the presence of a fatty oil is desirable.

In the appended claims, the term viscous hydrocarbon oil" is to. be understood to comprehend oils having a Saybolt universal viscosity at 100 F. of 50 seconds or more.

What I claim is:

1. A lubricant comprising a viscous hydrocarbon oil and a small amount, sufficient to impart extreme pressure properties to the oil, of a phosphine containing an organic substituent.

2. A lubricant comprising a viscous hydrocarbon oil and less than substantially 5% of a phosphine containing an organic substituent.

3. A lubricant comprising a viscous hydrocarbon oil and less than substantially 1% of a phosphine containing an organic substituent.

4. A lubricant comprising a viscous hydrocarbon oil and from about 0.1% to about 0.5% of a phosphine containing an organic substituent.

5. A lubricant comprising a viscous hydrocarbon oil and a small quantity of an aryl phosphine.

6. A lubricant comprising a viscous hydrocarbon oil and a small quantity of tri phenyl phosphine. l

'7. A lubricant comprising a viscous hydrocarbon oil and. a small amount, suflicient to impart extreme pressure properties to the oil, of a phosphine having the formula.

wherein R RF, and R are of the group consisting of aliphatic, aromatic, hydroaromatic and heterocyclic radicals. 1

8. A lubricant comprising a viscous hydrocarbon oil and a small quantity of a phosphine containing a halogenated organic substituent.

9. A lubricant comprising a viscous hydrocarbon oil and a small quantity of a compound from the group consisting of phcsphines containing an organicsubstituent and the halogen substi tution products thereof. L

10. The method. of reducing friction betwee relatively moving metallic surfaces which comprises maintaining therebetween a film of lubri eating oil and at the same time chemically acting upon suchsurfaces by means oi. .a phosphine containing an organic substituent, said phosphine being present in said film in relatively small amounts.

- JOHN G. BU'IZ. 

